1. Field of the Invention
This invention relates to pluggable electronic circuit package assemblies and more particularly to pluggable electronic circuit package assemblies for edge type connectors and the like, and as well as to heat sink housings per se of such assemblies.
2. Description of the Prior Art
Electronic circuit package assemblies can be categorized into pluggable and non-pluggable types. With regards to pluggable circuit package assemblies, these may be further categorized into edge connector types and non-edge connector types.
Examples of non-pluggable types are described in U.S. Pat. Nos. 4,444,994, 4,546,410, 4,563,725, and 4,774,632.
Briefly, the assembly of U.S. Pat. No. 4,444,994, has a quick disconnect finned heat sink which has as a part thereof a mounting plate for mounting electrical components requiring cooling. An electrical terminal block is affixed to the sink and provides common connection points for connecting the wires of the mounted electrical component and the wires of the remote peripheral control circuitry for operating the mounted component.
In the assembly of U.S. Pat. No. 4,546,410, an electrical circuit package has an electrically insulating housing that is mounted to a finned heat sink with screws. The heat generating electrical component with its accompanying lead frame are housed in the opening of the housing and is mounted on the top side of an electrically insulative thermally conductive substrate which is part of the circuit package. A rupturable membrane containing thermal grease is positioned between the substrate and the heat sink and is ruptured during assembly of the circuit package to the heat sink when the membrane becomes compressed between the substrate and the heat sink.
Top and bottom thermal plates are used in the package assembly of U.S. Pat. No. 4,563,725. The input/output (I/O) terminals of the circuit components, i.e. semiconductor chip carriers having an integrated circuit (IC) chip encased or bonded thereto, are bonded to a circuitized polyimide flexible substrate and the two are sandwiched between the two thermal plates. Inwardly projecting studs or pillars are formed on the bottom plate and pass thru aligned apertures in the circuitized tape to make contact with the components. The top plate is directly in contact with the component or alternatively may have individual inwardly projecting resilient means making contact with the components. Resilient U-shaped clamps, or alternatively bolts, engage the outer surfaces of the thermal plates to keep the assembly together.
In one of the IC chip packages of U.S. Pat. No. 4,474,632, two identical hermetically sealed chip holding assemblies are mounted on opposite sides of a silicon interconnect module. The latter has multiple interconnected conductor layers which interconnect I/O pads located on its two planar surfaces. Each chip holding assembly has outer and inner silicon plates separated by silicon spacers in which the chips are housed. The chip I/Os are solder bumps which are compressively mated with the conductor pads on the facing surface of the inner plate, the latter pads being connected by conductive vias of the inner plate to conductor pads located on the opposite surface of the inner plate. The last mentioned pads in turn mate with the I/O pads on the particular adjacent surface of the interconnect module, and may be solder bonded together or compliantly compressed together. In the chip holding assembly, copper gauze is inserted between the outer plate and the top of the chip so as to resiliently urge the pads of the chip to contact the adjacent pads of the inner plate. The external I/Os for the package are provided by pads located on the periphery of the interconnect module. In another package of this patent, the chip I/Os are placed in direct compressive contact with the interconnect module pads, the chips being located between a pair of spaced finned heat sink and copper gauze being inserted between the heat sink plates and the tops of the chips to resiliently urge the chips towards the interconnect module.
Examples of pluggable assemblies of the non-edge type are described in U.S. Pat. Nos. 3,506,877, 4,092,697, 4,415,025, 4,707,726, 4,716,494 and 4,716,498. Generally, in these types, IC chips are mounted to chip carrier substrates, which in turn are electrically connected to a printed circuit (PC) board or the like.
In the module assembly of U.S. Pat. No. 3,506,877, a metal header with a row of feed thru pins is adapted to be plugged into a standard companion connector. Mounted to the header is the flange formed at an edge of a heat sink shield plate. The pins of the header feed thru a row of openings in the flange and are electrically insulated from the flange and header by glass seals. Located between the row of pins and the heat sink is a PC board which has a surface bonded by a thermal conductive adhesive to the heat sink. Circuit components are mounted on the other surface of the board, the latter having a peripheral row of I/O pads that are affixed, e.g. by soldering, welding, etc., to the heads of the feed thru pins of the header. Another component populated PC board is similarly bonded to the other side of the heat sink shield plate.
In the assembly of U.S. Pat. No. 4,707,726, the three external electrode conductors of an encapsulated discrete power transistor protrude from one of its sides and are plugged into and soldered to appropriate conductive receiving holes of a PC board. On another of its sides, the discrete transistor is inserted into a channel formed on one surface of a heat sink. The heat sink has fins formed on its opposite surface. The transistor is maintained in contact with the walls of the channel of the heat sink by a spring beam plate.
U.S. Pat. Nos. 4,092,697, and 4,415,025 and 4,716,494 disclose circuit package assemblies in which the IC chip is bonded to a pinned substrate having an array of pins connected to the I/O terminals of the particular chip.
In the case of the assemblies of U.S. Pat. Nos. 4,092,697 and 4,415,025, the pinned substrate is a circuitized ceramic substrate having an the array of pins which in turn are adapted to be plugged into a corresponding array of conductive holes of a PC board. A finned heat sink is hermetically sealed to the substrate and encloses the chips.
In the case of the package assembly of U.S. Pat. No. 4,716,494, an IC chip is located in the recess of a pinned chip carrier having an array of pins that plug into a corresponding array of receptacles of a pinned electrical socket, the pins of the latter in turn being plugged into plated thru holes (PTHs) of a PC board. A bow-shaped spring clips a heat sink, which has circular stacked fins, to the housing of the socket.
U.S. Pat. No. 4,716,498 describes rack mounted electric circuit module assemblies which use pin connectors that plug into mating socket connectors mounted on a PC board secured to the rack. The pin connectors are part of the module assembly and have receptacles for receiving the pins of feed thru pin header, the heads of the pin headers being connected by discrete flying lead conductors or a flexible conductor tape to the circuitized substrate to which an IC carrier is connected.
Edge type connectors generally have one or more linear arrays of spring contacts mounted in housing or header. For single sided applications, the spring contact arrays are aligned in the same direction. For double sided applications, the spring contacts of one or more of the arrays are aligned in the same direction and the spring contacts of one or more of the other arrays are aligned in the opposite direction. The spring contacts are adapted to mate with the I/O pads of a PC card or board that are arranged in a corresponding linear array or arrays which are peripherally located on one (i.e. single sided) or both (double sided) surfaces of the board near a predetermined edge of the board.
By way of example, European Patent Application No. No. 86113669.6, published May 6, 1988, discloses a package assemble which is used with an edge type connector of the zero insertion force (ZIF) kind. In this assembly, circuit modules containing IC chips are mounted to one surface, referred to as the populated surface, of a PC card. The card is sandwiched in a cassette which has a molded plastic side cover adjacent to the unpopulated surface of the card and a metal heat sink cover adjacent to the populated surface of the card. Two opposite edges of the rectangular shaped card extend outwardly from the two cassette covers providing exposed extensions. Located on each extension is a linear array consisting of a pair of parallel rows of I/O pads, there being a pair on both the opposing surfaces of the card in proximity to each of the last two mentioned edges. Each such edge is associated with a ZIF connector. More particularly, when the two edges are inserted, i.e. plugged, into their respective associated ZIF connector, each of the two peripheral I/O pad arrays located on the opposite surfaces of the card extension associated with the particular edge are adapted to mate with a corresponding one of the linear arrays of opposing spring contacts of its respective associated ZIF connector. Deformable metal taps formed on the metal heat sink cover are inserted into openings in the plastic cover and are bent to affix the metal cover to the plastic one. For retaining the card and cassette in the connectors, a pair of resilient bow shaped elongated members are housed in a handle which is affixed to the plastic cover. The handle is actuated to plug the card into the connectors, causing a tip of each bow member resiliently to engage a pocket formed in the connector adjacent to it.
In the Technical Document Product Specification 108-1095, entitled "Micro-Edge SIMM Connectors", published by AMP Incorporated, there is shown a package assembly which includes a PC card with a row of single in line memory modules (SIMM) mounted to a surface of the card and with a row of I/O pads along one edge of the card. The I/O pads mate with a row of cam operated spring contacts mounted in an edge type connector when the edge of the card is plugged into the connector and the contacts are cammed to their closed position.
With the concurrent advances in the related technologies providing higher circuit densities of the individual chips per se, higher density input/output connections of the chips and/or cards, and/or higher wiring density and the decreased wiring dimensions and spacings of the conductors of the card, there is a need for improved circuit package assemblies for accommodating these advances that are highly reliable, relatively simple, easy to assemble/disassemble, and which have improved thermal and/or environmental enhancement characteristics, and which were heretofore not available in the prior art. With the advent of direct chip attach (DCA) technology, i.e. electrical and mechanical attachment of integrated circuit chips directly to an organic printed circuit card or the like, the need is even more acute.